This application claims the priority of German patent document 198 47 985.9, filed Oct. 17, 1998 (17.10.98) and PCT International Patent Application No. PCT/EP99/06854, filed Sep. 16, 1999 (16.09.99), the disclosure of which is expressly incorporated by reference herein.
The invention relates to a container for receiving an operating medium for the operation of a fuel cell.
Energy in fuel cells is obtained by a controlled reaction between hydrogen and oxygen, during which hydrogen ions and oxygen ions are bonded to form water at a membrane inside the fuel cell. It is known to supply the operating media in gas form from tanks belonging to the fuel cell. It is also known to obtain the operating medium oxygen from the ambient air.
Particularly when fuel cells are being used in non-stationary installations, such as for example vehicles, there are both restrictions with regard to the space available and safety concerns with regard to the transportation and/or storage of relatively large volumes of gaseous hydrogen. Also, particularly for fuel cell vehicles, it is necessary to ensure a sufficiently widespread supply of operating media, in particular hydrogen.
It has been proposed to obtain the hydrogen required from a hydrogen-containing or hydrocarbon-containing operating medium, preferably liquid methanol, the in a gas generation system by steam methanol reforming.
A significant advantage of using methanol is that methanol can be made available at filling stations at significantly lower cost than, for example, gaseous hydrogen. Prototypes of fuel cell vehicles are operated with chemically highly pure methanol, since undesirable admixtures in the operating medium may poison chemically active regions. By contrast, for economic operation of fuel cell vehicles in which it is possible to fill up with methanol at filling stations, the customary transport distances and transport methods mean that it is necessary to take into account a higher degree of contamination of the methanol than is tolerable in the various chemically active regions of the fuel cells.
One object of the present invention is to provide a container for receiving an operating medium for fuel cells which is also suitable for methanol with a low degree of purity.
This and other objects and advantages are achieved by the container according to the invention, which has at least one inlet for media, preferably operating media, a first outlet and a second outlet. The container is divided by at least one permeable component into at least an inlet-side interior space, and an interior space which is remote from the inlet. The first outlet is arranged in the inlet-side interior space and the second outlet is arranged in the interior space which is remote from the inlet.
In a first preferred embodiment, the permeable component is provided for the purpose of separating impurities out of the operating medium.
In another preferred embodiment, the permeable component is in contact with a first type of the operating medium in the inlet-side interior space and with a second type of the operating medium in the interior space which is remote from the inlet. The first type of the operating medium is less pure than the second type of the operating medium.
In a further preferred embodiment, the first type of the operating medium has a different chemical composition From the second type of the operating medium.
In still another preferred embodiment, the permeable component is in contact with operating medium in the inlet-side interior space and with impurities in the operating medium in the interior space which is remote from the inlet.
It is advantageous if the permeable component has a semi-permeable membrane and/or a molecular sieve and/or a ceramic body and/or a particle filter.
It is expedient to provide a connection to a vacuum pump in the interior space of the container which is remote from the inlet. A higher throughput of the medium passing through the permeable component is possible by reducing the partial pressure on one side.
A further expedient configuration is to provide a connection to a purge device in the outlet-side region of the container. The throughput of the medium passing through the permeable component can be increased by purging the interior space which is remote from the inlet with a purge medium.
In an especially preferred configuration, the operating medium contains methanol. It is expedient if the purified methanol can be supplied to a gas generation system for obtaining hydrogen. Furthermore, it is expedient if the impurities can be supplied to a catalytic burner unit. In this way, hydrocarbon impurities obtained from the methanol purification can advantageously be used to obtain process heat for any reformers, evaporators and/or gas-cleaning units.
It is preferred to use the container in a fuel cell vehicle.
Another preferred use of the container is in a refuelling installation for fuel cell vehicles. In this case, the vehicle can be filled with purified or at least pre-purified operating medium.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.